DEFINITION AND PROVINCE OF LOGIC. 13 



its precursor or as its accompaniment and necessary 

 condition, a corresponding improvement in the notions 

 and principles of logic received among the most ad- 

 vanced thinkers. And if several of the more difficult 

 sciences are still in so defective a state ; if not only so 

 little is proved, but disputation has not terminated 

 even about the little which seemed to be so ; the 

 reason perhaps is, that men's logical notions have not 

 yet acquired the degree of extension, or of accuracy, 

 requisite for the estimation of the evidence proper to 

 those particular departments of knowledge. 



7. Logic, then, is the science of the operations 

 of the understanding which are subservient to the 

 estimation of evidence : both the process itself of pro- 

 ceeding from known truths to unknown, and all intel- 

 lectual operations auxiliary to this. It includes, 

 therefore, the operation of Naming ; for language is 

 an instrument of thought, as well as a means of 

 communicating our thoughts. It includes, also, 

 Definition, and Classification. For, the use of these 

 operations (putting all other minds than one's own 

 out of consideration) is to serve not only for keeping 

 our evidences and the conclusions from them perma- 

 nent and readily accessible in the memory, but for so 

 marshalling the facts which we may at any time be 

 engaged in investigating, as to enable us to perceive 

 more clearly what evidence there is, and to judge 

 with fewer chances of error whether it be sufficient. 

 The analysis of the instruments we employ in the 

 investigation of truth, is part of the analysis of the 

 investigation itself; since no art is complete, unless 

 another art, that of constructing the tools and fitting 

 them for the purposes of the art, is embodied in it. 



Our object, therefore, will be to attempt a correct 



